public class Student {
    public static void main(String args[]){
        String id = "20233011031";
        System.out.println(id);
        int length = id.length();
        System.out.println("字符串的长度为："+length);
        char ch = id.charAt(3);
        System.out.println("字符串中的第4个字符为："+ch);
        char a[] = new char[2];
        id.getChars(9,11,a,0);
        System.out.println("字符串中的最后两个为："+ String.valueOf(a));
    }
}
